Field stitching approach for the wave optical modeling of black silicon structures
The interest in black silicon structures as an anti-reflective interface at the front side of silicon solar cells increased strongly with the rise of diamond wire sawing. The application of optical modeling in order to predict optimal structure parameters could be highly valuable. However, due to the random nature of the structure as well as dimensions in the range of the wavelengths of interest, optical modeling is still a challenge. Within this work, the stitching method of rigorously calculated fields is extended and applied to a black silicon structure. A Fourier transform is used to determine the angular intensity distribution in the far field. In combination with the OPTOS formalism, this allows modeling of silicon substrates with black silicon front side and shows a reasonably good agreement with optical measurement results. Implementing the investigated structure into a solar cell configuration reveals not only a low reflectance but also a very good light trapping performance close to that of a Lambertian scatterer.